CN102495295B - Measuring method of capacitance characteristic of semiconductor film material and apparatus thereof - Google Patents

Abstract

The invention provides a measuring method of capacity and quality of a specific capacitor. The specific capacitor is made of a semiconductor film material. A measurable parameter eta is set as capacitance difference rate. The capacitance difference rate is defined as a ratio of a difference of a capacitance actual value Cs and a capacitance test value Cp and an average value of the capacitance actual value Cs and the capacitance test value Cp. Through measuring the capacitance test value Cp, a conductance value Gp and test frequency omega, the capacitance difference rate eta, the capacitance actual value Cs, a series resistance Rs, high frequency loss tg delta or a corresponding loss angle delta are calculated. Simultaneously, the invention provides an apparatus which implements the measuring method. The method and the apparatus have the following advantages: only a metal platform and a suspension type mercury probe are needed, and the apparatus is simple; in a whole operation process of preparing and measuring the specific capacitor, a sample is not damaged; there is no special requirement to a substrate and interface structure of a measured semiconductor sample, and a range of application is wide; the capacitance difference rate is employed to measure the capacitance actual value of the specific capacitor and monitor the quality of the specific capacitor, operation is convenient and fast, and data is reliable.

Description

A kind of measuring method of semiconductor film material capacitance characteristic and device

Technical field

The present invention relates to the semiconductor material technology, particularly a kind of measuring method of semiconductor film material capacitance characteristic and device.

Background technology

Document: SOLID STATE MEASUREMENTS INC (US) .Apparatus for characterization of electrical properties of a semiconductor body.US5036271,1991-07-30, reported a kind of measurement mechanism of semiconductor chip electrical characteristics, this device adopts mercury probe to contact with sample surfaces, form schottky junction electric capacity, bottom electrode is metal pedestal, and it and Semiconductor substrate are Ohmic contact.Document: John D.Wiley and G.L.Miller.Series Resistance Effects in Semiconductor CV Profiling.IEEE Transactions on Electron Devices, Vol.ED-22, No.5, (1975) P265, introduced the measuring method of non-conductive substrate semiconductor film (for example being grown in the GaAs film of mixing on the chromium substrate), employing is respectively done a schottky junctions contact and Ohmic contact point at film surface, at this moment measure junction capacity, resistance in series can be very large, directly affects the electric capacity actual value.Document: M.Binet.Fast And Nondestructive Method Of C (V) Profiling Of Thin Semiconductor Layers On An Insulating Substrate.Electron.Lett.Vol.11.P580. (1975), reported the semiconductive thin film (for example GaAs film of GaAs field effect transistor use) of growing on the High resistivity substrate, measurement mechanism adopts two homalographic mercury probes, they lean on very closely, only at a distance of 50 μ m, therefore resistance in series is very little, can ignore the impact of junction capacity.

Comprehensive above-mentioned document, prior art is measured semiconductor junction electric capacity, can be divided into following dual mode:

1, measurement mechanism adopts single mercury probe.The Surface Contact of mercury and conductive substrates film sample form schottky junction electric capacity, and sample substrate is Ohmic contact.This measurement pattern, resistance in series is generally very little, can ignore the impact of junction capacity.If measure non-conductive substrate semiconductor film sample, schottky junctions contact and Ohmic contact point are made in the sample surfaces homonymy, and resistance in series is generally all very large, when measuring junction capacity, must consider the impact of resistance in series.

2, adopt A pair of mercury probes measurement device dielectric substrate film sample.Form simultaneously two schottky junctions contacts at sample surfaces, if they lean on very closely (for example: at a distance of 50 μ m), resistance in series can be very little, can ignore the impact of junction capacity.Otherwise resistance in series is very large, will count it to the impact of junction capacity.

Summary of the invention

The objective of the invention is for above-mentioned technical Analysis, a kind of measuring method and device of semiconductor film material capacitance characteristic are provided, this device is made a particular comparator with semiconductor samples, introduce a measurable parameter η (electric capacity difference rate), both described particular comparator, characterized again the capacitance characteristic of measured material, particular comparator will become will further investigate semiconductor film material impurity concentration and the most important basic components of interface state density from now on.

Technical scheme of the present invention:

The measuring method of a kind of particular comparator capacity and quality, semiconductor film material is made a particular comparator, and to set a measurable parameter η be electric capacity difference rate, described electric capacity difference calibration justice is the difference of electric capacity actual value Cs and capacity measurement value Cp and the ratio of its mean value, by measuring capacity measurement value Cp, electric conductivity value Gp and the test frequency ω of particular comparator, calculate electric capacity difference rate η, electric capacity actual value Cs, resistance in series Rs, high-frequency loss tg δ or corresponding loss angle δ, computing formula is:

$\mathrm{\&eta;}=\frac{{2G}_P^2}{{\mathrm{<figure-callout\; id="2"\; label="G\; P"\; filenames="HDA0000124725120000011.png"\; state="\{\{state\}\}">G</figure-callout>}}_P^{}+{2\mathrm{\&omega;}}^2{\mathrm{<figure-callout\; id="2"\; label="C\; P"\; filenames="HDA0000124725120000011.png"\; state="\{\{state\}\}">C</figure-callout>}}_P^{}},$ $C_S=\frac{2+\mathrm{\&eta;}}{2-\mathrm{\&eta;}}\&CenterDot;C_P,$ $R_S=\frac{2\mathrm{\&eta;}}{2+\mathrm{\&eta;}}\&CenterDot;\frac{1}{G_P},$

$\mathrm{tg\&delta;}=\mathrm{\&omega;}{R}_S{C}_S=\sqrt{\frac{2\mathrm{\&eta;}}{2-\mathrm{\&eta;}}},$ $\mathrm{\&delta;}=\mathrm{<figure-callout\; id="2"\; label="arctg"\; filenames="HDA0000124725120000011.png"\; state="\{\{state\}\}">arctg</figure-callout>}\sqrt{\frac{2\mathrm{\&eta;}}{2-\mathrm{\&eta;}}}.$

a kind of measurement mechanism of described semiconductor film material capacitance characteristic, comprise insulating base, metal platform, probe support, microscope for observing, mercury bulb, mercury probe and lifting runner, metal platform, probe support and microscope for observing are fixed by channel-section steel and screw and insulating base respectively, the disc semiconductor samples is adhesively fixed on metal platform by coupling liquid, mercury bulb is placed in the surface of semiconductor samples, probe support is the inverted L shape structure, the mercury probe is fixed by the crossbeam of lifting runner and probe support, mercury probe and lifting runner consist of the screw thread transmission and rotate the lifting runner makes the lifting of mercury probe, mercury probe lower surface applies pressure on mercury bulb and forms circular mercury layer, microscope for observing is provided with the micrometer scale, the bottom electrode lead-in wire is drawn from metal platform, the top electrode lead-in wire is drawn from the mercury probe, the bottom electrode lead-in wire is connected with top electrode and is connected with the electric capacity conductivity meter by wire respectively.

The diameter of described circular mercury layer is 0.5-5.0mm.

The principle of work of measurement mechanism:

Rotating the lifting runner descends the mercury probe, make mercury bulb contact semiconductor sample, the mercury bulb that is crushed forms circular mercury layer and is covered in the semiconductor samples surface, jointly consists of a particular comparator by mercury probe, mercury bulb, circular mercury layer, semiconductor samples, coupling liquid and metal platform like this.Regulate the diameter that the lifting runner can change circular mercury layer, simultaneously the particular comparator capacity also oblong mercury layer diameter change and change, the diameter of circular mercury layer can be by the micrometer tape measure of microscope for observing.With upper/lower electrode lead-in wire 15 and 16 access electric capacity conductivity meters, capacitance Cp and the electric conductivity value Gp of particular comparator can measure.

The ultimate principle of measuring method:

This measuring method is made a particular comparator to semiconductor film material, and set a measurable parameter η (electric capacity difference rate), described electric capacity difference calibration justice is the difference of electric capacity actual value Cs and capacity measurement value Cp and the ratio of its mean value, by measuring capacity measurement value Cp, electric conductivity value Gp and the test frequency ω of particular comparator, calculating parameter η, electric capacity actual value Cs, resistance in series Rs, high-frequency loss tg δ or corresponding loss angle δ.

Principle and formula proving are as follows:

True capacitor is comprised of electric capacity actual value Cs and resistance in series Rs.That obtain when usually adopting the electric capacity conductivity meter to measure is shunt capacitance value Cp and electric conductivity value Gp.Suppose that test frequency is ω, between the test value of the actual value of series connection and parallel connection, have following two groups of relational expressions:

$\left\{\begin{array}{cc}{R}_S=\frac{G_{\mathrm{<figure-callout\; id="2"\; label="P\; G\; P"\; filenames="HDA0000124725120000011.png"\; state="\{\{state\}\}">P</figure-callout>}}}{G_P^{}}& ---\left(1a\right)\\ C_S=\frac{{\mathrm{<figure-callout\; id="2"\; label="G\; P"\; filenames="HDA0000124725120000011.png"\; state="\{\{state\}\}">G</figure-callout>}}_P^{}+{\mathrm{\&omega;}}^2{\mathrm{<figure-callout\; id="2"\; label="C\; P"\; filenames="HDA0000124725120000011.png"\; state="\{\{state\}\}">C</figure-callout>}}_P^{}}{{\mathrm{\&omega;}}^2{C}_P}& ---\left(1b\right)\end{array}\right.$

$\left\{\begin{array}{cc}{G}_P=\frac{{\mathrm{\&omega;}}^2{R}_{\mathrm{<figure-callout\; id="2"\; label="S\; C\; S"\; filenames="HDA0000124725120000011.png"\; state="\{\{state\}\}">S</figure-callout>}}{C}_S^{}{}_2^{}}{1+{\mathrm{\&omega;}}^2{R}_S^2{C}_S^2}& ---\left(2a\right)\\ C_P=\frac{C_S}{1+{\mathrm{\&omega;}}^2{R}_S^2{C}_S^2}& ---\left(2b\right)\end{array}\right.,$

In formula: Cp is the capacity measurement value, and Gp is the conductivity test value, and Cs is the electric capacity actual value, and Rs is resistance in series, and ω is applying frequency.

Consider now (2b) formula:

For ideal capacitor, resistance in series is zero, gets Rs=0, so, Cs=Cp, two kinds of electric capacity differences are zero; For true capacitor, resistance in series is non-vanishing, gets Rs＞0, so, Cs＞Cp.In other words, between electric capacity actual value Cs and capacity measurement value Cp, always have difference, and difference is less, more trend is desirable, and the electric capacity quality is more excellent; Otherwise difference is larger, more departs from ideal, and the electric capacity quality is more bad.

For capacity and the quality of describing true capacitor, we define a parameter η, called after electric capacity difference rate, and it is the difference of electric capacity actual value Cs and capacity measurement value Cp and the ratio of its mean value, that is:

$\mathrm{\&eta;}\&equiv;\frac{C_S-C_P}{\frac{1}{2}(C_S+C_P)}---\left(3\right)$

(3) formula is namely:

$\frac{C_P}{C_S}=\frac{2-\mathrm{\&eta;}}{2+\mathrm{\&eta;}}---\left(4\right)$

By (1a) formula and (1b) formula can obtain:

${\mathrm{\&omega;}}^2{R}_S^2{\mathrm{<figure-callout\; id="2"\; label="C\; S"\; filenames="HDA0000124725120000011.png"\; state="\{\{state\}\}">C</figure-callout>}}_S^{}=G_P{R}_S\frac{C_S}{C_P}---\left(5\right)$

By (5) formula and (2b) formula can obtain:

$\frac{C_P}{C_S}=1-G_P{R}_S---\left(6\right)$

Can be obtained by (4) formula and (6) formula:

$G_P{R}_S=\frac{2\mathrm{\&eta;}}{2+\mathrm{\&eta;}}---\left(7\right)$

Also can be obtained by (1a) formula:

$G_P{R}_S=\frac{G_P^2}{{\mathrm{<figure-callout\; id="2"\; label="G\; P"\; filenames="HDA0000124725120000011.png"\; state="\{\{state\}\}">G</figure-callout>}}_P^{}+{\mathrm{\&omega;}}^2{C}_P^2}---\left(8\right)$

Merge (7) formula and (8) formula, just obtain capacitance difference value rate η:

$\mathrm{\&eta;}=\frac{{2G}_P^2}{{\mathrm{<figure-callout\; id="2"\; label="G\; P"\; filenames="HDA0000124725120000011.png"\; state="\{\{state\}\}">G</figure-callout>}}_P^{}+{2\mathrm{\&omega;}}^2{C}_P^2}---\left(9\right)$

(9) formula has a lot of important using values: first applying frequency is that the electric capacity conductivity meter of ω is measured true capacitor, and when obtaining test value Cp and Gp, electric capacity difference rate (parameter η) has also obtained; It two is that electric capacity actual value Cs can be determined by parameter η, can be obtained by (6) formula and (7) formula:

$C_S=\frac{2+\mathrm{\&eta;}}{2-\mathrm{\&eta;}}\&CenterDot;C_P---\left(10\right);$

It three is that the quality of actual capacitance is represented by resistance in series Rs and high-frequency loss tg δ usually, and here they can electricity consumption tolerance rate (parameter η) show.Can obtain resistance in series by (7) formula:

$R_S=\frac{2\mathrm{\&eta;}}{2+\mathrm{\&eta;}}\&CenterDot;\frac{1}{G_P}---\left(11\right)$

Can obtain high-frequency loss (being ω RsCs) by (5) formula, (7) formula and (10) formula:

$\mathrm{tg\&delta;}=\mathrm{\&omega;}{R}_S{C}_S=\sqrt{\frac{2\mathrm{\&eta;}}{2-\mathrm{\&eta;}}}---\left(12\right)$

(12) formula or be expressed as loss angle:

$\mathrm{\&delta;}=\mathrm{<figure-callout\; id="2"\; label="arctg"\; filenames="HDA0000124725120000011.png"\; state="\{\{state\}\}">arctg</figure-callout>}\sqrt{\frac{2\mathrm{\&eta;}}{2-\mathrm{\&eta;}}}---\left(13\right).$

Suppose to press in advance the η set-point and divide capacitor grade, the measured capacitance device is carried out the electric capacity conductance measurement.Obtain the η test value, η set-point and η test value relatively contrast, and just can determine measured capacitance device grade at once.Meet η set-point requirement, reliable test result, data are effective; Otherwise, should again prepare particular comparator, retest.

Advantage of the present invention:

The present invention only needs a metal platform and a suspension type mercury probe, and device is simple; The all operations were process of preparation and measurement particular comparator is not damaged sample; Substrate and interfacial structure to tested semiconductor samples do not have special requirement, and the scope of application is wider; Adopt electric capacity difference rate to measure electric capacity actual value and its quality of monitoring of particular comparator, convenient and swift, data are reliable.

Description of drawings

Accompanying drawing 1 is this particular comparator measurement mechanism structural representation.

In figure: 1. insulating base 2. metal platform 3. probe support 4. microscope for observing 5. mercury bulb 6. mercury probe 7. lifting runner 8. channel-section steels and screw 9. semiconductor samples 10. circular mercury layer 12. micrometer scale 13 bottom electrodes lead-in wire 14. top electrodes lead-in wire 15. electric capacity conductivity meter of coupling liquid 11.

Embodiment

Describe the detailed process of utilizing measurement mechanism test particular comparator in detail below in conjunction with accompanying drawing.

a kind of measurement mechanism of described semiconductor film material capacitance characteristic, as shown in drawings, comprise insulating base 1, metal platform 2, probe support 3, microscope for observing 4, mercury bulb 5, mercury probe 6 and lifting runner 7, metal platform 2, probe support 3 and microscope for observing 4 are fixing with insulating base 1 by channel-section steel and screw 8 respectively, disc semiconductor samples 9 is adhesively fixed on metal platform 2 by coupling liquid 10, mercury bulb 5 is placed in the surface of semiconductor samples 9, probe support 3 is the inverted L shape structure, mercury probe 6 is fixed by lifting runner 7 and the crossbeam of probe support 3, mercury probe 6 consists of the screw thread transmission and rotates lifting runner 7 with lifting runner 7 makes 6 liftings of mercury probe, mercury probe 6 lower surfaces apply pressure on mercury bulb 5 and form circular mercury layer 11, microscope for observing 4 is provided with micrometer scale 12, bottom electrode lead-in wire 13 is drawn from metal platform 2, top electrode lead-in wire 14 is drawn from mercury probe 6, bottom electrode lead-in wire 13 is connected with top electrode and 14 is connected with electric capacity conductivity meter 15 by wire respectively.

Process of measurement: rotate the lifting runner mercury probe is descended, make mercury bulb contact semiconductor sample, the mercury bulb that is crushed forms circular mercury layer and is covered in the semiconductor samples surface, jointly consists of a particular comparator by mercury probe, mercury bulb, circular mercury layer, semiconductor samples, coupling liquid and metal platform like this.Regulate the diameter that the lifting runner can change circular mercury layer, the diameter of circular mercury layer is 0.5-5.0mm, simultaneously the particular comparator capacity also oblong mercury layer diameter change and change, the diameter of circular mercury layer can be by the micrometer tape measure of microscope for observing.With upper and lower contact conductor access electric capacity conductivity meter, capacitance Cp and the electric conductivity value Gp of particular comparator can measure.

Utilize this measurement mechanism to make a particular comparator to semiconductor film material, and to set a measurable parameter η be electric capacity difference rate, described electric capacity difference calibration justice is the difference of electric capacity actual value Cs and capacity measurement value Cp and the ratio of its mean value, by measuring capacity measurement value Cp, electric conductivity value Gp and the test frequency ω of this particular comparator under circular mercury layer different-diameter, calculate electric capacity difference rate η, electric capacity actual value Cs, resistance in series Rs, high-frequency loss tg δ or corresponding loss angle δ, computing formula is:

$\mathrm{\&eta;}=\frac{{2G}_P^2}{{\mathrm{<figure-callout\; id="2"\; label="G\; P"\; filenames="HDA0000124725120000011.png"\; state="\{\{state\}\}">G</figure-callout>}}_P^{}+{2\mathrm{\&omega;}}^2{\mathrm{<figure-callout\; id="2"\; label="C\; P"\; filenames="HDA0000124725120000011.png"\; state="\{\{state\}\}">C</figure-callout>}}_P^{}},$ $C_S=\frac{2+\mathrm{\&eta;}}{2-\mathrm{\&eta;}}\&CenterDot;C_P,$ $R_S=\frac{2\mathrm{\&eta;}}{2+\mathrm{\&eta;}}\&CenterDot;\frac{1}{G_P},$

$\mathrm{tg\&delta;}=\mathrm{\&omega;}{R}_S{C}_S=\sqrt{\frac{2\mathrm{\&eta;}}{2-\mathrm{\&eta;}}},$ $\mathrm{\&delta;}=\mathrm{<figure-callout\; id="2"\; label="arctg"\; filenames="HDA0000124725120000011.png"\; state="\{\{state\}\}">arctg</figure-callout>}\sqrt{\frac{2\mathrm{\&eta;}}{2-\mathrm{\&eta;}}}.$

Following examples are the measurement result of utilizing this measurement mechanism.

Embodiment 1:

Measured object: certain large shell schottky diode;

Test data: capacity measurement value Cp=124PF, electric conductivity value Gp=20 μ s, test frequency 1MHz;

Result of calculation: η=6.56 * 10 ^-4, Cs=124.1PF, Rs=33 Ω, tg δ=2.56 * 10 ^-2, corresponding loss angle δ angle is 1 ° 30 '.

Embodiment 2:

Measured object: certain factory's varactor;

Test data: capacity measurement value Cp=55PF, electric conductivity value Gp=23.6 μ s, test frequency 1MHz;

Result of calculation: η=4.63 * 10 ^-3, Cs=55.3PF, Rs=195 Ω, tg δ=6.80 * 10 ^-2, corresponding loss angle δ is 3 ° 56 '.

Embodiment 3:

Measured object: N/N ⁺Type silicon epitaxial wafer 95-3-303 ^#:

Test data: capacity measurement value Cp=147PF, electric conductivity value Gp=19.7 μ s, test frequency 1MHz;

Result of calculation: η=4.56 * 10 ^-4, Cs=147PF, Rs=23.1 Ω, tg δ=2.13 * 10 ^-2, corresponding loss angle δ is 1 ° 13 '.

Practice show this measuring method and application of installation respond well, device is simple, preparation and measure all operations were process of particular comparator, do not damage sample, adopt electric capacity difference rate to measure electric capacity actual value and its quality of monitoring of particular comparator, convenient and swift, data are reliable.

Claims (3)

1. the measuring method of a particular comparator capacity and quality, it is characterized in that: semiconductor film material is made a particular comparator, and to set a measurable parameter η be electric capacity difference rate, described electric capacity difference calibration justice is the difference of electric capacity actual value Cs and capacity measurement value Cp and the ratio of its arithmetic mean, by measuring capacity measurement value Cp, electric conductivity value Gp and the test frequency ω of particular comparator, calculate electric capacity difference rate η, electric capacity actual value Cs, resistance in series Rs, high-frequency loss tg δ or corresponding loss angle δ, computing formula is:

2. measurement mechanism of semiconductor film material capacitance characteristic as claimed in claim 1, it is characterized in that: comprise insulating base, metal platform, probe support, microscope for observing, mercury bulb, mercury probe and lifting runner, metal platform, probe support and microscope for observing are fixed by channel-section steel and screw and insulating base respectively, the disc semiconductor samples is adhesively fixed on metal platform by coupling liquid, mercury bulb is placed in the surface of semiconductor samples, probe support is the inverted L shape structure, the mercury probe is fixed by the crossbeam of lifting runner and probe support, mercury probe and lifting runner consist of the screw thread transmission and rotate the lifting runner makes the lifting of mercury probe, mercury probe lower surface applies pressure on mercury bulb and forms circular mercury layer, microscope for observing is provided with the micrometer scale, the bottom electrode lead-in wire is drawn from metal platform, the top electrode lead-in wire is drawn from the mercury probe, the bottom electrode lead-in wire is connected with top electrode and is connected with the electric capacity conductivity meter by wire respectively.

3. the measurement mechanism of semiconductor film material capacitance characteristic according to claim 2, it is characterized in that: the diameter of described circular mercury layer is 0.5-5.0mm.

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